Conventionally, in a camera system to which a digital camera connected with an external strobe, and an image processing computer used to immediately browse sensed image data are connected, the external strobe undergoes light control via a dedicated strobe cable. After images are sensed, sensed image data stored in the digital camera are transferred to the external image processing computer via a data communication means such as USB, IEEE1394, or the like equipped in the main body.
FIG. 10 shows an example of the arrangement of a conventional camera system. In FIG. 10, a digital camera (CAMERA) 1100 has two communication interfaces to which a strobe dedicated bus (XBUS) 1101 and data communication high-speed serial bus (USB) 1107 are connected. An XHUB 1105 is connected to the CAMERA 1100 via the XBUS 1101, and serves to distribute a strobe control signal sent from the CAMERA 1100 to two external strobes (SPEEDLIGHT) 1102 and (SPEEDLIGHT) 1103. When the user of this camera system makes an image sensing operation, the external strobes 1102 and 1103 emit light in synchronism with an exposure function of the CAMERA 1100, thus sensing an image. The sensed image data is sent to an image processing computer (PC) 1106 via the USB 1107, and undergoes an image process. After that, the processed image data is displayed on a display 1104.
A control circuit for the SPEEDLIGHT 1102 receives electric power from a battery pack (BAT) 1108 including four size AA batteries, and also receives electric power required to emit light from a layer-built battery pack (BAT) 1109. Likewise, a control circuit for the SPEEDLIGHT 1103 receives electric power from a battery pack (BAT) 1110, and also receives electric power required to emit light from a layer-built battery pack (BAT) 1111.
On the other hand, in another conventional method, a plurality of still cameras (to be also simply referred to as “cameras” hereinafter) are connected, and an object image is sensed from different directions by these cameras simultaneously or sequentially at given time intervals. In still another image sensing method, using a plurality of strobe emission devices, the shade of an object is controlled to have a required direction and light amount distribution.
In operation control for implementing such image sensing method, since a camera main body has a dedicated terminal used to control the image sensing start timing and strobe emission timing, control via wires of the dedicated terminal or synchronous control using infrared rays or the like is done.
For example, Japanese Laid-Open Patent No. 2000-338567 or the like has proposed a method in which a communication means such as IEEE1394 or the like is arranged in addition to an infrared ray communication means, and time interval information from an infrared ray communication until an actual strobe emission timing is transmitted via that communication means.
FIG. 11 shows the arrangement of an image sensing system 800 described in Japanese Laid-Open Patent No. 2000-338567 or the like.
An image sensing system 800 has an arrangement in which a plurality of strobe emission devices 820-1, 820-2, . . . are connected to a camera 810.
The camera 810 comprises a controller 811, communication unit 812, image sensing unit 813, A/D converter 814, processor 815, recorder 816, timing generator 817, and IR emission unit 818.
The plurality of strobe emission devices 820-1, 820-2, . . . have the same arrangement, i.e., each strobe emission device comprises a controller 821, communication unit 822, strobe emission unit 823, timing generator 824, and IR emission unit 825.
In such image sensing system 800, especially, the camera 810 comprises the communication unit 812 such as IEEE1394, and the IR emission unit 818 serving as an infrared ray emission means, and each strobe emission device 820-x (x: 1, 2, . . . ) comprises the communication unit 822 such as IEEE1394, and the IR emission unit 825 serving as an infrared ray emission means. Before strobe emission, the communication unit 812 of the camera 810 exchanges information that pertains to a time interval (delay time) from when the IR emission unit 818 of the camera 810 emits infrared rays until the strobe emission unit 823 of the strobe emission device 820-x emits light.
However, the aforementioned prior art suffers the following problems. That is, independent communication interfaces and cables must be equipped for external strobe control and data transfer, and connections are complicated. Also, independent dedicated communication terminals must be equipped for respective purposes, and it is difficult to attain a size reduction of the housing size of the camera.
In the strobe, electric power required for emission control and that required to emit light are supplied from independent battery packs. It is a common practice to supply electric power required for emission control mainly from size AA batteries stored in the strobe, and to supply electric power required to emit light from the layer-built battery pack connected to the strobe.
Therefore, connections of the plurality of battery packs are troublesome, and if electric power of the battery pack for control is used up, an image sensing operation is disabled even when the battery pack for light emission can still supply sufficient electric power.
In the conventional image sensing system described in Japanese Laid-Open Patent No. 2000-338567 or the like, a communication using infrared rays (that between the IR emission units 818 and 825) is required in addition to a wired communication (that between the communication units 812 and 822), as shown in FIG. 11. For this reason, it is difficult to attain a cost reduction and size reduction of the apparatus or system. In addition, the following problems remain unsolved. For example, normal light emission is disturbed if infrared rays are intercepted, and a time delay occurs between emission and reception of infrared rays.